Hybrid Vehicle Technology Report Engineering Essay

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This report will investigate and discuss the technologies involved in hybrid vehicle passengers car. The technologies covered in this report will be battery, power train, motor, engine control etc.

Two kinds of power sources are used in this system in order to run the vehicle. These are electric motor and a petrol engine. The system usually operates in series hybrid or parallel hybrid.

In a series hybrid system, an engine power generator is used to produce electricity for the motor to move the wheels. The battery of this system is getting charged by the constantly working very efficiency low output gasoline engine when it is running. This is all controlled by the computer.

The series hybrid system uses a motor that is bigger and heavier compare to parallel hybrid system, this is the reason why the engine has to produce more power which requires a very high and maximum productivity (NZAA Inc, 2011).

Another type of hybrid system is parallel hybrid technology, both the engine and the motor are used to produce power to drive the wheels. The transmission and computer permits all the parts in the system to operate together. The brakes in this system usually generate the charge for the battery and this is the reason why they use the small battery pack. Alternatively, the drive motor can also be used to supplement recharging when it needs more power, this process works just like an alternator in normal cars. The engine is attached directly to the wheels in this system, this helps it to give more needed power and makes it as a better option for the highway, because it is more straight forward than converting mechanical power to electricity and back. However, city driving efficiency is reduced because when stopping and going, there are high variations in power that forces the engine to work inefficiently (Union of concerned scientists, 2010)


History of the hybrid system

The hybrid system was introduced around 1825 and 1965. The steam cars were invented at this stage. The first electric vehicle was introduced by a Scottish Robert Anderson. At the beginning of the twentieth century, so many hybrid vehicles were manufactured, a gasoline was used to supplement a battery pack by Krieger Company while Henry Ford used a pipe line as an advent.

Over the years, the productions of hybrid cars have increased because of the high demanding of low emission vehicles and constant increase of fuel prices. Different car makers now are manufacturing hybrid vehicles, for example Toyota Prius, Toyota Siena, Dodge Ram, Mazda Tribute, Honda Civic, Ford Escape, Porsche Cayenne, Chevrolet Tahoe and GMC Yukon are all in the market right now. This shows that the hybrid vehicles system is the future of the automotive industry (Admin, 2006).

Types of hybrid system.

General, there are three types of hybrid systems. These are series, parallel and series parallel.

Series type: this system uses the electric motor as the main energy source to get the wheels going. Later, the inverter is used to direct the power to the electric motor. At this time, the battery is also getting charged by the power. The major basic components are internal combustion engine, a battery, inverter and an electric motor.


The main reason for this system to be called series is because the energy is coming from the combustion engine, it continues to go through different series of components until it gets to the electric motor, which supports to run the wheels. This hybrid type uses a different system that does not need a gear transmission (Toyota Motor Corporation, 2011).

Series/ Parallel type: this system holds together the advantages and difficulties of the series and parallel drivetrains.

Toyota Hybrid System

Union concerned scientist 2011 state that, this system can use an electric motor and combustion engine to run the wheels. The power split device is used to separate the power that is provided by the gasoline to move the wheels, while the unused power is directed to the generator for charging the battery or preserving it into the electric motor. The power source that comes from the electric motor is also being controlled at a low speed, while the high speed power that is provided by the combustion engine chamber is also being managed. This type of system is better compare to series system because of its operating mechanism.

Parallel type: the major components of this system are electric motor, power control unit, battery, combustion engine and a transmission. It uses both electric motor and internal combustion engine to run the wheels. When the motor receives the power from the battery, it uses it to drive the wheels and can also be used as a generator for charging the battery. During the car movement, the motor cannot be used to generate the electricity because the power usually moves in parallel and this is the main reason for it to be named parallel system.


(Lemieux, J, 2010)

Major components of the hybrid drive system

Conventional drives vehicles are made of power train system that contain an internal combustion engine while the hybrid vehicle system consist of battery, power train, motor, engine control, generator, gasoline engine and the fuel tank. These components perform different roles in the system, and they will all be explained below.

Battery: the hybrid battery is made of lithium, this battery has the ability to allow the charging rate that has a limited damage to the battery, and the parts of the battery are made of smaller cells that are linked with an electrical framework. This structure controls what batteries to use and charge depending on the condition of the cell (state of charge).

Hybrid Battery Cut-away

The manufactures have been waiting for so long for this type of battery because of its capabilities of charge rate and power output. Even the life span has been increased due to the introduction of the copper from the lead. If you compared these to lead batteries you can see that by weight it carries three times more energy and produce up to fifteen times the power and by volume it carries two times more energy and produce up to ten times the power. These batteries are charged between the regenerative brake systems, combustion engine alternator and plug in from an outside power source. The special computer is kept to monitor the charge level of the battery, it helps it to remain balance in order to protect it from exploding due to the high density of electrolytes (2CarPros, 2010).

Power train:

The various hybrid powertrain structures use different strategies to optimize powertrain behavior. Therefore, the demands placed on the internal combustion engine differ, depending on the type of hybrid system that is selected. For example, in vehicles that use a parallel hybrid layout, the engine should be optimized for a large part of its operating area to exploit the full potential of the hybrid technology. Vehicles that utilize power-split hybrid designs should have the engine optimized for a specific operating curve. http://www.fev.com/content/public/default.aspx?id=557

Motor: the planetary gear set is used to put together components such as an electric motor and a generator and a very high efficiency gasoline engine. Prius uses this method to create gear arrangement that need no transmission. The hybrid engine is very small, in order for it to achieve a high and quick acceleration, a lot of things need to happen at once and this is supported by the reduction pistons and their load.


In hybrid system, electric motor is the main source of the power, this can work as a generator’s source because of the addition of the advanced electrons which produce more energy. During low speed, this motor converts the frictional energy and kinetic energy that provides electric energy that is used for driving. When the engine is turned on, the same procedure occurs, it can work individually or sometime can rely the battery too. During high acceleration, a lot of power is drained and used and at a low acceleration the power is sent back to the battery (Ofria, C. 2008)

Power control Unit: the hybrid system contains well advanced equipment that involves the inverter, AC/DC current converter and a voltage boosting converter. The direct current (DC) from the battery is converted by the inverter to AC, this process turns the electric motor or make it mobile. It can also convert the AC to DC from the motor to the battery. In order for the battery to retain the charge that is being used, this process has to occur. This becomes like a relay thyristor because of the conversion of the small to large current to have the motor working.

Inverter usually works as a self-inductance of the windings of the motor, this causes it to resist current change at any time. Once the current has been drawn from the battery, it is the inverter that permits it to go through the windings, due to the voltage preserving, this process occurs when winding voltage becomes less than battery voltage.1118542634_69051

If we take a look at the battery that supplies 200V, the voltage boosting converter can change it to 600V â€" 650 V to the electric motor. This uses sensors for the current conversion and gives the required voltage to the motor at the right moment and supply the much needed operating torque. It can also convert current from high voltage to as low as 12V for the electrical parts such as ECU in the car (Toyota motor corporation, 2011)

Generator: This is the major source of power in the hybrid system, it is where the gas engine power gets converted to electrical power to drive the motor or charge the battery and this is mainly used on series hybrid cars (Nice & Layton, 2011)

Gasoline engine and fuel tank: reduction of the emission is the main purpose for the gasoline engine and this can be supported by the help of the advanced technologies. Some research are said that about 1000 of battery electrons that provides energy is the same as 1 gasoline gallon, because the battery produces a lot of electrons, the more voltage and a very good charging system is needed. The fuel tank in this system is very small and light which means it only takes less fuel. The gasoline engine and the electric motor can be switched off while the car is stationary and this helps to reduce about 25% to 35% of fuel emissions. A special computer device has been designed in order to control the electric drive system in order to stop and save the gasoline to get in (Dunn, P. 2006)

Transmission: According to green car congress 2010 state that Daimler Chrysler, GM and BMW are collaborating together in designing the new hybrid system transmission that will be a low and high transmission (ECVT) modes, this system is known as 2 mode hybrid, due to high power handling capabilities and efficiency for different applications in vehicles, the four fixed gear ratios can be integrated. When the ECVT and four fixed gear ratios operate, the electric motors and can be used for boosting as well as regenerative braking. The four sixed gears are superior compared to two ECVT mode because of its performance in six different condition. These are:

The input split ECVT mode or nonstop variable mode 1, works from the starting of the vehicle through the second fixed gear ratio.

Compound split ECVT mode or constantly variable mode 2, performs after the second fixed gear ratio.

The internal combustion engine can be boosted or capture and store power from regenerative braking, coasting and deceleration by the first fixed gear ratio and electric motor.

The boost and braking can also be available during the second gear ratio with one electric motor.

With two electric motors and third fixed gear ratio, a boost or braking can be available.

Fourth fixed-gear ratio with one electric motor available for boost/braking

The automatic hybrid system can perform similar to the conventional automatic system in terms of mechanical operation, however, the hybrid transmission can work in four fixed gear ratios or in infinitely variable gear ratios.

Advantages of hybrid system:

This system is very good in terms of fuel consuming

They are quiet because they use electric motor to run

Good for the environment because they give less emission

They are very economical since they use both electric motor and gasoline engine to run.

Disadvantages of hybrid system:

The hybrid system is less popular compared to the conventional drive system, this makes it hard to fix it or diagnose it if something is wrong.

The vehicle itself and the parts can be expensive.

The electrical power that is in the system can be very dangerous because it can carry up to 240V of a direct current, this will need extra precautions when dealing or operate it.

There are not many technicians to date to deal with the Hybrid system


From the information covered in this report, we learn that the advantages of having hybrid systems are incomparable with the disadvantages of having one. The main benefit is that hybrid cars are contributing to the efforts to reduce pollution and since the world is now lacking fuel, hybrids are even more important. This system will help the community by preserving energy for the next generation as well as keeping our environment clean and producing less noise from the gasoline engines.

This report on hybrid systems is based on Toyota and Honda production since they are very common in our country. More companies are producing these types of cars now because this is the only way forward for everything and I hope other car manufactures that are not yet producing them will soon start to take action to manufacture more types of these vehicles. Hybrids will help in maintaining our planet, helping to give a sustainable life and bright future for the next generations.